N-substituted amino anilines



United States Patent N-suasrirurun .aMING ANILIPJES Elmore Louis Martin, Wilmington, Del, assignor to E. 1. du Pont de Nemours and Compwy, Wilmington, Del., a corporation of Delaware No Drawing. Application Qctober 22, 1%52, Serial No. 316,113

'7 Claims. or. ass-sea This invention relates to new N-substituted aminoanilines which are useful as photographic developing agents. More particularly it relates to N-alltyl-N-(sulfoarallryl)- anilines.

Various aryldiamiues have been used as photographic developing agents but the most important of them, namely, para-phenylenediamine and its simple N,N'-dialkyl derivatives have the disadvantage that they are absorbed by the skin and give rise to dermatitis. Since these agents are strong developers and couple with color formers during the development of latent silver halide images to produce quinoneimine or azornethine dye images in situ with the silver halides they are used in most commercial processes of color photography. Their toxicity, however, constitutes a health hazard in photographic processing laboratories which is undesirable.

An object of this invention is to provide a new class of N-substituted aminoanilines. A further object is to provide such compounds which are good photographic developing agents. A still further object is to provide a new class of N-alkyl-N-(sulfophenyl)-anilines which are good developing agents and are substantially free from toxic effects. Still other objects will be apparent from the following description of the invention.

This application is a continuation-in-part of Martin application Ser. No. 163,090, filed September 19, 1956, now abandoned.

It has now been found that new compounds having the formula:

where n is an integer of 210, alkyl contains l-6 carbons and R is hydrogen, alkyl or alkoxy, are particularly useful as color-coupling photographic developing agents. These compounds are very soluble, substantially nonirritant, active developers.

In Formula 1 suitable radicals for R include H, CH3, Cal-Is, CH(Cl-l3)2, OCHs, OCaHs, and are preferably one hydrogen or alkyls or alkoxy radicals of l3 carbons.

It has been found essential to have the tertiary nitrogen atom and the sulfophenyl group separated by at least 2 carbon atoms to obtain high developing activity. The compounds where n is 3 to 6 and allryl is of l to 4 carbon atoms are preferred. Where it is greater than 10, the compounds are still active developers but the developer difiuses into and washes out of the film less rapidly.

The compounds of Formula I may be obtained by the following series of reactions: (a) Preparation of an N-alkyl-N(omega-phenylallryl)aniline by reaction of an N-allryl aniline such as methyianiline, ethylaniline, n-propylaniline, isopropylaniline, butylaniline, pentylaniline, hexylaniline with a suitable phenylalkyl halide containing 2 to 10 carbon atoms in the alkylene radical,

'7 line, N-ethyl-m-methylaniline,

Z,?l*3,l32 Patented Aug. 23, 1955 ICC e. g., phenylethyl bromide, phenylbutyl bromide, phenylhexyl bromide or phenyldecyl bromide in which the aryl and halogen groups are on the opposite ends of the straight chain alkylene radical. This reaction is usually effected under alkaline conditions; ([2) preparation of N-alkyl-N(omega-sulfophenylalkyl)aniline by the reaction of the tertiary aniline obtained in step (a) with hot concentrated sulphuric acid; (0) preparation of the corresponding p-nitroso-N-alkyl-N omega-sulfophenylalkyl) aniline by reaction of the compound obtained in step (b) with nitrous acid; and (d) reduction of the nitroso compound suitably with iron or catalytically with iron or catalytically with hydrogen to the corresponding amine.

By starting with m-toluidine, N-methyl-rn-methylani- N-ethyl-m-isopropylaniline, N-hexyl-rn-methylaniline, N-hexyl-m-ethylaniline, etc.; m-anisidine, m-phenetidine, N-methyl-m-ethoxyaniline, N-ethyl-m-ethoxyaniline, N-methyl-m-isopropoxyaniline, N-ethyl-m-isopropoxyaniline, N-hexyl-m-methoxyaniline, N-hexyl-m-ethoxyaniline, etc.; in place of aniline in the above syntheses, the corresponding substituted compounds falling with Formula I can be made.

The following examples further illustrate but are not intended to limit the invention.

EXAMPLE I N-ethyl-N-(fi-phenyiethyl) aniline A mixture of 100 grams (0.8 mole) of ethylaniline, 140 grams (0.75 mole) of phenylethyl bromide and 130 grams (0.8 mole) of diethylaniline was heated on a steam bath for 16 hours. The mixture was treated with 10% sodium hydroxide solution until alkaline to litmus, the organic layer was separated and was dried with solid sodium hydroxide. There was obtained 136 grams of N-ethyl-N- (B-phenylethyl -aniline boiling at 01 5 2 /4 N -ethyl-N fl-sulfophenylethyl aniline To cc. of concentrated sulfuric acid was added 35 grams of N-ethyl-N-(fi-phenylethyl)aniline with stirring, the temperature being kept below C. by occasional cooling. The solution was heated on a steam bath for 30 minutes followed by 10 minutes at l1()l20 C. after which test portions were completely soluble in dilute alkali. The temperature was raised to 140 C. for a few minutes and after cooling the solution was poured onto ice, whereupon a solid separated. After standing for four hours in an ice bath the mixture was filtered, washed with a small amount of cold water, and air dried. The yield of colorless inner salt of N-ethyl-N-(B-sulfophenylethyl)-aniline was 43 grams.

1 fophenylethyl)auiline compound, obtained as described in the preceding paragraph, in 45 cc. of concentrated bydrochloric acid was added 25 grams of ice, whereupon the hydrochloride separated in a crystalline form. A solution of 10.5 grams of sodium nitrite in 20 cc. of water was added slowly during the course of three hours, the temperature being kept at 0 C. by means of external cooling. The mixture was stirred for an additional period of two hours at 0 C., the test for free nitrous acid remaining positive. The hydrochloride of the nitroso compound partially separated in crystalline form but was readily soluble and was reduced to the amino compound without further purification.

p-Amino-N-ethyl-N- (p-sulfophenylethyl) -aniiine hydrochloride To the above reaction mixture was added small portions of iron dust until the solution was colorless when spotted on filter paper, the temperature being maintained below 30 C. by controlling the rate of addition of the iron powder and by means of external cooling. As soon as the solution was colorless, the temperature was increased to 50 C.fand the solution made alkaline (pH 9-10) with 10% potassium hydroxide solution. A small amount of sodium hydrosulfite was added to prevent discoloration. The precipitated ferrous hydroxide was removed by filtration and the filter cake was extracted with small portions of hot water until test portions of the filtrate indicated the absence of color developer when tested with phenylmethylpyrazolone and potassium ferricyanide. The resulting solution was made acid to Congo red with hydrochloric acid and the precipitated sulfur was removed by filtration. The colorless filtrate was evaporated to dryness on a steam bath under-reduced pressure. The

solid residue was extracted with small portions of hot methanol until test portions indicated the absence of color developer. The resulting methanol solution of the color developer was evaporated to dryness under reduced pressure in a water bath at 7080 C. and extracted a second time with methanol. The resulting solution (800 cc.) was cooled in a Dry Ice bath until crystals began to form, then the mixture was diluted with an equal volume of anhydrous ether. After cooling to 40 C., the colorless crystals were collected, washed with a cold 50-50 mixture of methanol-ether, then with ether, and finally with petroleum ether. The hydrochloride thus obtained was dried under reduced pressure over phosphoric anhydride. The compound is readily soluble in water, alcohol, acids, and bases- The neutral equivalent of the compound as determined by titration using phenolphthalein indicator was 200. The calculated neutral equivalent of p-amino-N-ethyl-N-(fi-sulfophenylethynaniline hydrochloride dihydrate is 196.

EXAMPLE 11 N -ethyl-N ('y-phenylpropyl aniline A mixture of 400 grams of phenylpropyl bromide and 532 grams of ethylaniline was heated on a steam bath with stirring under-nitrogen for 16 hours. A solution of 80 grams of sodium hydroxide in 400 cc. of water was added and the organic layer separated and dried over solid sodium hydroxide. Distillation gave a 92% yield .of N-ethyl-N-('y-phenylpropyl)aniline boiling at 168- 172 C./2 mm.

N-ethyl-N-(' -sulfophenylpropyl)aniline To ISO-cc. of concentrated sulfuric acid was added with mechanical stirring 120 grams of N-ethyl-N-(yphen- 1 ylpropyl)aniline, the temperature rising to 110 C. dur- After a few minutes, the aqueous layer was decanted, the.

oil was washed with a small amountof cold water and seeded. After about 30' minutes, the oil had solidified. The inner salt was collected, washed with a small amount of cold water, and crystallized from 300 cc. of water. After cooling to C. there was obtained 128 grams of colorless, glistening, free-flowing crystals. The neutral equivalent using phenolphthalein indicator was 332. The

7 calculated neutral equivalent for N-ethyl-N-(y-sulfophenylpropyl) aniline monohydrate is 337. p -Nitroso-N- etlzyl-N-(' -sulfophenylpropyl) -anilz'ne To a mixture of 300 cc. of hydrochloric acid and 100 cc. 'of water was added 132 grams of 'N-ethyl-N-(y-sulfophenylpropyDanilin'e monohydrate and the solution was cooled to 0 C. by means of external cooling. While being .stirred' mechanically andmaintained at ()1 C. by

means of external cooling, asolution of 28 grams of sosium ferricyanide.

(:3. dium nitrite in 100 cc. of water was added during the course of two hours. The stirring was continued at 0 C. for an additional period of three hours during which time the test for free nitrous acid remained positive. The

crude nitroso compound, was used directly for reduction to the amino compound.

p-Amino-N-ethyl-N-(y-sulfophenylpropyl) -aniline' liydrochloride A few drops of methylhexylcarbinol was added to the reaction mixture of the preceding paragraph followed alkaline (pH 910) with sodium hydroxide solution,

a small amount of sodium hydrosulfite added, andthe mixture filtered. The filter cake was extracted repeatedly with hot water until a test portion of the filtrate no longer gave a magenta dye when treated withphenylmethylpyrazolone followed by the addition of potas- The resulting aqueous solution was acidified to Congo red with hydrochloric acid, the precipitated sulfur removed by filtration, and the filtrate evaporated to dryness under reduced pressure in a bath at 75-85 C. The solid residue was extracted with small portions of hot methanol until the extracts no longer gave a positive test for color developer. The methanol solu tion was evaporated to dryness under reduced pressure and'the compound extracted a second time with methanol.

After evaporation to dryness, the compound was purified as follows: To 30 grams of the crude product was added 250 cc. of pure methanol, the solution was filtered, rand the filtrate made up to a volume of 400 cc. After cooling to 40 C. in a Dry Ice bath, an equal volume of anhydrous ether was added slowly. The colorless precipitate was collected, washed with anhydrous ether, and finally with petroleum ether. After drying under reduced pressure over phosphoric anhydride there was obtained 25-28 grams of colorless crystalline compound. Electrometric titration with 0.1 normal sodium hydroxide solution indicated two end points, one at a pH of 5.1,

EXAMPLE III N -etlzyl-N delta-sulfophenyl butyl aniline This compound was prepared in the same manner as N-ethyl-N-('y-sulfophenylpropyl)aniline by substituting an equivalent amount of phenyl-n-butyl bromide for the phenylpropyl bromide.

p-Nitroso N-ethyl-N- delta- (p-sulfophenyl bulyl] aniline Seventy grams of N-ethyl-N-[delta-(p-sulfophenyl)- butyllaniline was dissolved in milliliters of hydro chloric acid plus 25 milliliters of water. Fourteen grams of sodium nitrite in 20 milliliters of water was added drop- After wise with stirring at 0 C. during 40 minutes. one hour of stirring, 400 milliters of water was added. The nitroso compound crystallized during 0.5 hour of stirring and was filtered off and washed with water; yield,

67 grams (93% p-A-mino-N-ethyl N- [delta-(p-sulfophenyl)butyl] aniline To a slurry of 60 grams of the nitroso compoundafieisa EXAMPLE IV p-Amino-N-erhyl-N['y-(p-sulfophenyl)propyll m-toluz'dine (A) N-eflzyl-N- ('y-phenylpropyl)-m-t0luidine.A mix ture of 200 parts of N-ethyl-m-toluidine, 300 parts of 'y-phenylpropyl bromide and 250 parts of diethylaniline was heated on a steam bath for hours. The reaction mixture was made alkaline with 33% sodium hydroxide solution and the organic layer was separated. Fractional distillation gave 310 parts of N-ethyl-N- ('y-phenylpropyl)-m-toluidine, B. P. 150-155 C. at 1 mm.

Analysis.Calcd. for C18H23NZ C, 85.31; H, 9.15; N, 5.53. Found: C, 85.25; H, 9.21; N, 5.36.

(B) N ethyl N [v-(p-sulf0phenyl)propyll-m-t0luidine.N-ethyl N ('y phenylpropyl)-m-toluidine (100 parts) was added in a thin stream with stirring to 275 parts of sulfuric acid. The resulting solution was heated to 110 C. and maintained at 110115 C. for 0.5 hour. After cooling, the reaction mixture was poured onto excess ice and the sticky reaction product was separated from the aqueous layer by decantation. The crude reaction product was washed twice with cold water by decantation and then warmed with a small amount of water whereupon a crystalline product was obtained. After cooling thoroughly, the crystalline reaction product was collected and washed with a small amount of cold water. Crystallization from dilute ethanol gave 102 parts of colorless crystals of N-ethyl-N-['y-(p-sulfophenyDpropyll-m-toluidine having a neutral equivalent of 333.0. The calculated neutral equivalent is 333.2.

(C) p-Nitroso-N-ethyl-N-['y-(p sulf0phenyl)propyll m-z0luidine.To a stirred solution of 33 parts of N-ethyl- N-Py-(p-sulfophenyhpropyl]-rn-toluidine in parts of concentrated hydrochloric acid and 10 parts of water was added during one hour, a solution of 7.2 parts of sodium nitrite in 10 parts of water. The temperature was maintained at 0-5 C. by means of external cooling. The reaction mixture was stirred for an additional period of one hour, during which time an oil separated that gradually solidified. After dilution with parts of water, the reaction product was filtered oil? and washed with cold water. It was only slightly soluble in hot water or alcohol. The yield of air-dried p-nitroso-N-ethyl-N-['y-(psulfophenyDpropyl] -m-toluidine was 26 parts.

(D) p-Amino-N-erhyl-N ['y(p sulf0phenyl)propyl]- m-t0luidine.Twenty-six parts of p-nitroso-N-ethyl-N- -(p-sulfophenyDpropyl] -n1-toluidine was dissolved in a solution of 3 parts of sodium hydroxide in 100 parts of water, charged into a shaker tube with 2 parts of palladium-on-charcoal catalyst and hydrogenated at 25-60 C. and 200-1000 lbs/sq. in. for one hour. The reaction mixture was filtered and the filtrate was acidified with hydrochloric acid to a pH of 5.2, whereupon the product separated. After cooling thoroughly, the crude reaction product was dissolved in excess dilute hydrochloric acid, the resulting solution was treated with decolorizing charcoal and the pH of the resulting colorless filtrate was adjusted to 5.2 by means of a saturated solution of sodium bicarbonate. The colorless, crystalline p-amino-N-ethyl- N- -(p-sulfonphenyl) propyl] -m-toluidine was collected and washed with water. It has the formula:

The compound is sparingly soluble in hot water and alcohol, readily soluble in mineral acid solutions as well as in alkali, hydroxide, carbonate and bicarbonate solutions. The yield was 12 patrs.

Analysis.-Calcd. for C1sH24O3N2S-1/2H2O: S, 9.00; N, 7.85; neut. equiv., 357.3. Found: S, 9.04; N, 7.84; neut. equiv., 358.0.

The corresponding homologues wherein the nuclear substituted alkyl group is methyl, propyl or isopropyl can be made in like manner by substituting for the N-ethylm-toluidine an equivalent amount of N-methyl-m-methylaniline, N-ethyl-m-isopropylaniline, N-hexyl-m-methylaniline,N-hexyl-'n-ethylaniline, etc.

EXAMPLE V p-A mino-N-ethyl-N-l'y-(p-sulfophenyl) -propyll -mphenetidine (A) N-etlzyl-N-(y phenylpropyl)-m-phenetidine.A

2 mixture of parts of N-ethyl-m-phenetidine (prepared as described by Bent, Dessloch, Fassett, James, Ruby, Steiner, Vittum and Weissberger, I. Am. Chem. Soc. 73, 3125 (1951)), 90 parts of 'y-phenylpropyl bromide and parts of diethylaniline was heated on a steam bath r added 5.6 parts of N-ethyl-N-('y-phenylpropyl)-m-phenetidine. The resulting solution was stirred and maintained at l05ll0 C. for 0.5 hour. After cooling, the reaction mixture was poured onto excess ice and the aque ous layer was decanted from the sticky reaction product.

. The crude reaction product was washed twice by decantation and on standing slowly solidified.

(C) p-Nitr0s0-N-ethyl-N- ['y(p sulfophenyl) -pr0pyl]- m-phenetidine.To a solution of 17 parts of N-ethyl-N- -(p-sulfophenyl)propyl]-m-phenetidine in 20 parts of concentrated hydrochloric acid and 3 parts of water was added during the course of one hour, a solution of 3.5 parts of sodium nitrite in 5 parts of water. The temperature was maintained at 05 C. by means of external cooling. The nitroso compound separated first as an oil that slowly solidified. After dilution with 58 parts of water, the reaction product was collected and washed with water. The p-nitroso-N-ethyl-N- ['y- (p-sulfophenyl)- propyll-m-phenetidine is only slightly soluble in water or alcohol. The yield was essentially quantitative.

(D) p-Amiiw-N-ethyl-N-[v-(p sulfophenybpropyflm-phenezz'dine hydrochloride.-To the reaction mixture obtained by the nitrosation of 17 parts of N-ethyl-N-[y- (p-sulfophenybpropyl]-m-phenetidine as described above was added iron dust in small portions until the solution was colorless when spotted on filter paper, the temperature being maintained below 30 C. by means of external cooling. The resulting reaction mixture was made alkaline with 10% potassium hydroxide solution and a trace of sodium hydrosulfite was added. The reaction mixture was filtered, the filter cake was washed with warm water and the combined filtrates were acidified with hydrochloric acid. The resulting solution was evaporated to dryness in a water bath at 50 C. under reduced pressure and the residue was extracted with methanol. The methanol extract was concentrated to dryness and the residue developing conditions.

7 extracted with a small volume of methanol. Addition of ether caused the p-amino'N-ethyl-N-['y-(p-sulfophenyl)- propyll-m-phenetidine hydrochloride to separate as a colorless solid. It hadthe formula:

omomomO-s 0311-1101 The compound was collected, washed with ether and dried, over-phosphoric pentoxide under reduced pressure. The compound is very soluble in water, alcohols, and soluble in, acetone. A piece of exposed photographic film gave a. magenta dye when color developed in a color developer composition comprising the above developer HIN - and; phenylmethylpyrazolone.

The corresponding methoxy, propoxy and butoxy compounds'can be prepared in like manner by substituting for the N-ethyl-m-phenetidene in paragraph A of Example II an equivalent amount of m-anisidine, m-phenetidine,

. N-methyl-m-ethoxyaniline, N-methyl-m-isopropoxyaniline, 'N-ethyl-m-isopropoxyaniline, N-hexyl-m-methoxyaniline, N-hexyl-m-ethoxyaniline, etc.

While Examples I, II and V describe. the preparation of the hydrochlorides, other addition salts can be made by using other acids of organic and inorganic type. The salts of strong mineral acids, e. g., hydrochloric, sulfuric and phosphoric are preferred but the salts with acetic, propionic, oxalic acids, etc. are of utility. The compounds ofi this, invention are also readily isolated as described in Example III, as their inner salts.

gamma incomparison with the commercial developer, p; aminodiethylaniline, are important in development, Sig: nif cant increases are, shown for the cyan andgmajgenta monolayers. The new developers also cause, in general,

less fog thanthe p-aminodiethylaniline' Note that p-amino-N-ethyl-N-(sulfobenzyl) aniline is,

much lower in block speed and gamma, than thejnext' They may be used in developer formulations containing color formers for color development of exposed silver halide contained in gelatin or synthetic polymer binding Also they may BeemQ agents for silver halide grains. ployed for color development of photographic films containing immobile color formers incorporated in the film, particularly those films having as silver halide binders polyvinyl acetals of color-forming aldehydes as'described in U. S. Patent 2,397,864. The compounds of Formula I are not limited in their use as photographic developing agents but may also, be employed in dye manufacture as intermediates.

Table I.T able of evaluations of color developers MULTILAYER COATINGS (OF POLYVINYL ACETAL COLORJFORHERS CONTAINING DISPERSED SILVER HALIDE) Block Speed Gamma Fog Layer CD-l CD-2 OD-3 (JD-4 (JD-1 (JD-2 (JD-3 OD-4 (JD-1 QED-2 CD 3 312-4 MONOLAYER COATINGS (OF POLYVINYL ACE'I AL COLO R-FORMERS CONTAINING DISPERSE D SILVER HALIDE) Block Speed Gamma Fog Layer CD-l (ID-2 (JD-3 GD-4 (ID-5 (JD-1 (ID-2 (JD-3 CD-4 CD-5 CD-l 'GD-2 (JD-3 GD-4 4. 7 5. O 4. 5 4. 8 2. 2 2 12 2. 88 2. 64 3. 42 1. 27 0. l2 0. 08 V 0. 08 0. 19 4. 4 4 2 3. 4 4. 0 1. 4 1 61 1. 32 1. 39 l. 17 0. 94 0 07 0. 08 O. 07 0. 05' 4. 5 4. 3 3. 3 5. 1 0. 9 2 37 3 13 3. 24 2. 1. 27 O. 14 Q. 11 0. 10 0. 1-5

OD-1p-Aminodiethylaniline 0.0125 mole/liter).

CD5p-Aminc-N-ethyl-N-(sulfobenzyl) aniline (0.0125 mole/liter).

In addition, each developer solution also contained 25 grams NazCOs, 10 grams N32SO3 and 2 grams KBr per liter.

In the foregoing table the cyan, yellow and magenta coatings were dispersions of light-sensitive silver halides in polyvinyl acetal color formers of aromatic aldehydes of 1948, and Serial No. 29,921, filed May 28, 1948. In

the table/gamma refers to the development factor and fog refers to the density of development in the unexposed portion ofthe photographic film.

Block speed is an arbitrary figure indicating the speed of-the developer. If a developer has a block speed one unitless than another, this means that the photographic film will require about twice the exposure to give an image of the same density as the second under the same Gamma is defined in Neblette, Photography, 1942', page 412 (published by D. Van Nostrand (30.). Increased values of block speed and/or.

As many widely difierent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimed is:

where R is a member taken from the group consistingv of hydrogen, alkyl of l to 3 carbon atoms and alkoxy of l to 3 carbon atoms; Alkyl contains 1 to 6 carbon atoms 10 and n is a cardinal number from 2 to 10 inclusive, and 5. p Amino N ethyl N (delta sulfophenyltheir acid addition salts. butyl) -aniline.

2. The chemical compounds taken from the group con- 6. p Amino N ethyl N ['y (p sulfophenyl)- sisting of compounds of the general formula: propyH-m-toluidine.

Alkyl 5 7. p Amino N ethyl N ['y (p sulfopheny1)- Q propyH-m-phenetidine hydrochloride. HzN N\ (CHQPOSOJH References Cited in the file of this patent UNI T PA NT where n is a cardinal number from 3 to 6 inclusive and 10 :IED STA ES TE S alkyl contains from 1 to 4 carbon atoms, and their acid 2,163,166 Wflmanns June 1939 addition salts. FOREIGN PATENTS P Amlno N ethyl N sulfophenylethyl) 4 9 Great Britain July 30 1937 aniline hydrochloride.

4. p Amino N ethyl N ('y sulfophenylpropyD- 15 aniline hydrochloride. 

1. THE CHEMICAL COMPOUNDS TAKEN FROM THE GROUP CONSISTING OF COMPOUNDS OF THE GENERAL FORMULA: 